The field of art to which this invention relates is surgical implements and more specifically suture anchors for anchoring suture material to bone.
As the treatment of injuries to joints and soft tissue has progressed in the orthopaedic medical arts, there has been a need for medical devices which can be used to attach tendons, ligaments and other soft tissue to bone. When surgically repairing an injured joint, for example, it is often preferable to restore the joint by reattaching the damaged soft tissues rather than replacing them with an artificial material. Such restorations typically require the attachment of soft tissue such as ligaments and tendons to bone.
An increase in the incidence of injuries to joints involving soft tissue has been observed. This increased incidence may be due, at least in part, to an increase in participation by the public in various physical activities such as sports and other recreational activities. These types of activities may increase the loads and stress placed upon joints, sometimes resulting in joint injuries with corresponding damage to associated soft tissue. In 1991, for example, there were approximately 560,000 surgical procedures performed in the United States in which soft tissue was attached to a bone in various joints including the shoulder, hip and knee.
One conventional orthopaedic procedure for reattaching soft tissue to bone is performed by initially drilling holes or tunnels at predetermined locations through a bone in the vicinity of a joint. Then, the surgeon approximates soft tissue to the surface of the bone using sutures threaded through these holes or tunnels. This method, although effective, is a time consuming procedure resulting in the generation of numerous bone tunnels. A known complication of drilling tunnels across bone is that nerves and other soft tissue structures may be injured by the drill bit or orthopaedic pin as it exits the far side of the bone. Also, it is anatomically very difficult to reach and/or secure a suture/wire that has been passed through a tunnel. When securing the suture or wire on the far side of the bone, nerves and soft tissues can become entrapped and damaged.
In order to overcome some of the problems associated with the use of the conventional bone tunnel procedures, suture anchors have been developed and are frequently used to attach soft tissue to bone. A suture anchor is an orthopaedic, medical device which is typically implanted into a cavity drilled into a bone. Although less frequently, these devices have also been referred to as bone anchors. The cavity is typically referred to as a bore hole and usually does not extend through the bone. This type of bore hole is typically referred to as a xe2x80x9cblind holexe2x80x9d. The bore hole is typically drilled through the outer cortex layer of the bone and into the inner cancellous layer. The suture anchor may be engaged in the bore hole by a variety of mechanisms including friction fit, barbs which are forced into the cancellous layer of bone, etc. Suture anchors are known to have many advantages including reduced bone trauma, simplified application procedures, and decreased likelihood of suture failure due to abrasion on bone. Suture anchors may be used in the Bankart shoulder reconstruction for repairing the glenohumeral ligament and may also be used in surgical procedures such as rotator cuff repair and hip replacement. Also, such anchors may be used in repair of tendon tears by direct attachment of bone to bone.
Suture anchors typically have at least one suture attached. This may be by means of a hole or opening for receiving the suture(s). At least one end and typically both ends of the suture strand extend out from the bore hole and are used to attach soft tissue. The suture anchors presently described in the art may be made of absorbable materials which absorb over time, or they may be made from various non-absorbable, biocompatible materials. Although most suture anchors described in the art are made from non-absorbable materials, the use of absorbable suture anchors may result in fewer complications since the suture anchor is absorbed and replaced by bone over time. In addition, the use of absorbable suture anchors may reduce the likelihood of damage to local joints caused by anchor migration.
Although suture anchors for attaching soft tissue to bone are available for use by the orthopaedic surgeon, there is a constant need in this art for novel suture anchors having improved performance characteristics.
The device of the present invention calls for an implantable apparatus for wedging within an opening formed within a bone. The apparatus comprises a body which defines a perimeter and said perimeter defining at least one biting edge. A hole is defined by the body through which a suture is received for attachment through the device to the bone. The hole defined by the body may be nearer to one side of the perimeter in order to provide an imbalance of force to increase rotation of the device during the implantation procedure. The body in cross-section may have a perimeter which is substantially in the shape of a triangle, trapezoid or parallelogram. In this way the body may have two sides which diverge in a direction away from said hole, such that the rotation causes an edge formed by one of such sides to bite into the soft cancellous layer of the bone. In order to better distribute the forces acting on the device, the sides may be rounded so that the rounded edge will match with the size of the bore hold provided in the bone. In this way, maximum contact of the edge with the side of the hole in the bone is provided.
The edge may be formed by the intersection of planar or rounded sides or a combination of planar and rounded sides in order to optimize the biting action of the edge. The edge may also be provided with a single engaging tooth or a plurality of engaging teeth in order to improve the holding power, biting and/or placement of the device. The device may be triangular in shape and thus formed by three mutually adjacent sides.
The apparatus may further include a thin longitudinal stem portion which extends from the body. This stem portion is preferably detachable from the body and may be integral and formed with the body out of the same material and provided with a frangible portion or may be formed separately and fitted to the body.
The body may be made of any medical grade material and the stem may be made of a different medical grade material. The body and stem may be joined by a frangible portion which could be formed, for example, by two intersecting web portions in order to provide stability to the device during insertion while still providing the weakness necessary for fracture of the area.
The stem may be provided with a protrusion which mates with an implantation device in order to position the stem within the implantation device at an optimum position.
The body may be made of bioabsorbable material, a biocompatible metal, or a medical grade polymer for example. The body may be of a medical grade metal material and the stem made of a bioabsorbable polymer such that after fraction the anchor stays implanted but the stem portion remaining after fracture is absorbed by the body.
The invention includes a method of implanting a device for holding material in the bone which comprises accessing the bone and forming an opening therein for receipt of the device. The device is then gripped by a stem which extends from the device and is inserted into the opening by gripping such a stem. The stem is then detached from the device and the device is rotated in order to wedge within the opening formed in the bone.
The separation of the stem from the device may include either breaking a portion of the stem or device in order to separate the stem and device or separating the stem via a snap fit, interference fit, or other attachment mechanism.
The insertion device may include a stabilizing portion to prevent excessive premature rotation of the device and thus prevent premature fracture of any frangible portion of the stem. This however is not necessary in the method where the device is attached to the stem through an interference or frictional fit and the stem is merely removed from an opening in the device during the method of implantation.
In another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a suture, and means thereon for releasable connection to an inserter shaft; a boundary surface and a plow surface of the body intersecting to form a biting edge at the proximal end of the body; and the boundary surface and an abutment surface of the body intersecting to form a cam surface at the proximal end of the body; and the biting edge being adapted to be in engagement with a first wall portion of the bore and the cam surface being adapted to be in engagement with a second wall portion of the bore opposed to the first wall portion; wherein tension on the inserter shaft is operable to move the cam portion along the bore second wall portion and rotate the body in the bore such that the biting edge bites into the bore first wall portion to lock the body in the bore.
And in another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, the body defining a hole therethrough for retaining a suture, and the body having means thereon for releasable connection to an inserter shaft; the body having first and second opposite and parallel planar sides; the hole extending from the first side to the second side; each of the sides being provided with a rounded entryway leading to the hole, such that the hole is devoid of edges against which the suture can impinge.
In still another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and larger proximal end, means thereon for retaining a suture, and means thereon for releasable connection to an inserter shaft; the body distal end being of rounded configuration; a plow surface of the body being of rounded configuration in plan view; an abutment surface of the body opposite from the plow surface being of rounded configuration in plan view; and the abutment surface and a boundary surface of the body intersecting to form, in side elevational view, a rounded configuration; the rounded configurations being operable to guide entry of the body into the bore in the bone and to center the body in the bore.
And in yet another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, the body defining a hole therethrough for retaining a suture, and the body having means thereon for releasable connection to an inserter shaft; the hole being substantially elliptical in width-wise cross-section and having a major axis substantially normal to a minor axis; the major axis being aligned with a selected region of the body to direct stress from the suture toward the selected region of the body.
In another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, the body defining a hole therethrough for retaining a suture, and the body having means thereon for releasable connection to an inserter shaft; the body having first and second opposite sides; the hole extending from the first side to the second side; each of the sides being provided with a pathway extending from the hole to a boundary surface of the body, the pathway extending into the side of the body further than the diameter of the suture, such that the suture in the hole extends through the pathways and is disposed in the pathways removed from outer surfaces of the body first and second sides.
And in another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, the body having means thereon for retaining a suture, and a boundary surface having means therein for releasable connection to an inserter shaft; the means for releasable connection to an inserter shaft comprising a smooth-walled counterbore in the boundary surface, and a second bore in a bottom of the counterbore, the second bore being adapted to receive a threaded end portion of the inserter shaft and to be threadedly engaged thereby, and the counterbore being adapted to receive a cylindrically-shaped flexible tip portion of the inserter shaft; wherein flexing of the inserter shaft tip portion is permitted by the counterbore substantially without disturbing the engagement of the threaded end portion of the inserter shaft with the second bore.
The invention also comprises an installation tool for placing a suture anchor and a suture attached thereto in a bore in a bone, the tool comprising an elongated shroud having therein an internal opening; an inserter shaft slidably disposed in the internal opening; the suture anchor being releasably connected to a distal end of the inserter shaft; the shroud being of elastomeric material and configured to form first and second channels on opposite sides of the internal opening and adapted each to retain a portion of the suture attached to the anchor and extending proximally therefrom; each of the channels being formed such that a first portion of the channel at an outer surface of the shroud is narrower than a second portion of the channel spaced from the shroud outer surface; the suture portions being removable from the channel second portions by passing through the channel first portions, the elastomeric material deforming to allow the passage through the channel first portion.
The invention also comprises a bone anchor system comprising a suture anchor having means thereon for releasable connection to an installation tool; and the installation tool for placing the suture anchor and a suture attached thereto in a bore in a bone, the installation tool comprising an elongated shroud having an internal opening, and an inserter shaft slidably disposed in the internal opening, the inserter shaft comprising a proximal rigid portion connected to a distal flexible portion, the distal flexible portion being adapted to releasably connect to the suture anchor.
In another form of the invention, the bone anchor system comprises a suture anchor comprising a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a suture, and a boundary surface having means thereon for releasable connection to an inserter shaft; a suture connected to the anchor by the suture retaining means; and an inserter shaft connected to the anchor by the boundary surface inserter shaft connection means, the inserter shaft comprising an elongated rod having a handle at a proximal end thereof and the anchor disposed at a distal end thereof, the handle being generally of a xe2x80x9cTxe2x80x9d configuration in which the head of the xe2x80x9cTxe2x80x9d is angled 5xc2x0-45xc2x0 off normal to the axis of the rod, the handle being configured such that the head of the xe2x80x9cTxe2x80x9d fits a palm of an operator""s hand and a portion of the head of the xe2x80x9cTxe2x80x9d extending outwardly and distally from the rod proximal end is adapted to receive a thumb of the hand of the operator.
In still another form of the invention, the bone anchor system comprises a plurality of suture anchors, each comprising a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a suture, and means thereon for releasable connection thereof to an inserter shaft; an inserter shaft connected to each of the anchors by the releasable connection means; and a suture connected to each of the anchors by the suture retaining means, the sutures each being visually distinguishable from the remainder of the sutures, such that appropriate pairs of strands of the sutures may be visually identified by an operator.
In yet another form of the invention, the bone anchor system comprises a suture anchor comprising a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a plurality of sutures, and means thereon for releasable connection thereof to an inserter shaft; an inserter shaft connected to the anchor by the releasable connection means; and a plurality of suture strands connected to the anchor by the suture retaining means, the suture strands being visually distinguishable from each other, such that appropriate pairs of strands of the sutures may be visually identified by an operator.
In another form of the invention, the bone anchor system comprises a bone anchor having means thereon for retaining a suture; and the suture retained by the bone anchor; the suture being identifiable by color such that the suture can be distinguished from other sutures of other colors.
The present invention also comprises a method for disposing a suture anchor in a bore in a bone, comprising the steps of:
providing a suture anchor having thereon means for connecting a suture thereto, means for releasably connecting an inserter shaft thereto, a biting edge thereon, and a rounded cam surface on an opposite side of the anchor from the biting edge, the inserter connecting means being offset from a center of the anchor; and providing an inserter shaft comprising an elongated rod having a handle at a proximal end thereof and at a distal end thereof connected to the anchor by the releasable connecting means; and connecting a suture to the anchor by way of the means for connecting a suture to the anchor;
by manipulation of the inserter shaft, inserting the anchor in the bone with the biting edge adjacent a first wall portion of the bore in the bone and the rounded cam surface adjacent an opposite second wall portion of the bore;
pulling the inserter shaft so as to cause the rounded cam portion to move along the second wall portion and the anchor to rotate in the bore with the anchor biting edge biting into the first wall portion of the bore, whereby to lock the anchor in the bore with the suture extending from the bore; and
disengaging the inserter shaft from the anchor.